Fuel characteristics and fire behaviour in mature Mediterranean gorse shrublands

Since the early 1990s, Mediterranean gorse shrublands have expanded significantly in the Mediterranean regions of Spain mainly as a result of the increase in the frequency and extension of forest fires. Mediterranean gorse (Ulex parviflorus), which has been described as a degradation stage of forest communities after fire, has also been described as a fire-prone community. Thus, its presence increases the risk that new fires might occur. In spite of this evidence, there is little information on both the composition and structural characteristics of these communities or the relationship that might exist between these vegetation characteristics and fire behaviour. In this paper we present the results of a characterization of the vegetative structure (plant density, specific composition, biomass fractions, and horizontal and vertical fuel distribution) in Mediterranean gorse. We also analyse fire behaviour using indicators obtained at different scales. Our results show mature Mediterranean gorse shrublands to be communities with high biomass values (3000–4000 g m−2) and high horizontal and vertical vegetation continuity, in which the proportion of fine dead fuel fractions with low moisture content is around 50% of the total phytomass present. Ulex parviflorus is the dominant species and its degree of dominance is a key element in the behaviour of fire. Both the fire-line intensity values and the fire severity values observed can be considered high with respect to those observed in other Mediterranean communities, thus confirming Mediterranean gorse as a high-risk community.

[1]  B. Soto,et al.  Effects of burning on nutrient balance in an area of gorse (Ulex europaeus L.) scrub , 1997 .

[2]  Jordi Cortina,et al.  Climatic trends, disturbances and short-term vegetation dynamics in a Mediterranean shrubland , 2001 .

[3]  M. Bertrand.  M. Gounot, Méthodes d'étude quantitative de la végétation , 1971 .

[4]  Carlos Alberto Brebbia,et al.  Ecosystems and Sustainable Development II , 1999 .

[5]  E. Johnson,et al.  The Relative Importance of Fuels and Weather on Fire Behavior in Subalpine Forests , 1995 .

[6]  J. Peñuelas,et al.  Ground-based spectroradiometric estimation of live fine fuel moisture of Mediterranean plants , 1998 .

[7]  E. Johnson,et al.  The Need for Consideration of Fire Behavior and Effects in Prescribed Burning , 1995 .

[8]  J. Moreno,et al.  Methods for quantifying fire severity in shrubland-fires , 1998, Plant Ecology.

[9]  A. Floyd.  Effect of fire upon weed seeds in the wet Sclerophyll forests of Northern New South Wales , 1966 .

[10]  J. Cortina,et al.  Fire and torrential rainfall: effects on the perennial grass Brachypodium retusum , 2004, Plant Ecology.

[11]  C. H. Gimingham,et al.  Studies on fire in Scottish heathland communities. I: Fire characteristics , 1984 .

[12]  W. Platt,et al.  Ecology of Fire , 1984 .

[13]  A. Granström,et al.  Fire Severity and Vegetation Response in the Boreal Swedish Forest , 1996 .

[14]  T. Auld,et al.  Predicting patterns of post-fire germination in 35 eastern Australian Fabaceae , 1991 .

[15]  R. Burgan,et al.  Fuel Models and Fire Potential From Satellite and Surface Observations , 1998 .

[16]  B. Soto,et al.  Soil water balance as affected by throughfall in gorse (Ulex europaeus, L.) shrubland after burning , 1997 .

[17]  M. Luis,et al.  Effects of fire and torrential rainfall on erosion in a Mediterranean gorse community , 2003 .

[18]  W. Oechel,et al.  Fire intensity and herbivory effects on postfire resprouting of Adenostoma fasciculatum in southern California chaparral , 2004, Oecologia.

[19]  James K. Brown.  Bulk densities of nonuniform surface fuels and their application to fire modeling , 1981 .

[20]  Philip J. Riggan,et al.  Interaction of Fire and Community Development in Chaparral of Southern California , 1988 .

[21]  C. Francis,et al.  Runoff hydrographs from three Mediterranean vegetation cover types. , 1990 .

[22]  L. Trabaud.  Etude du comportement du feu dans la Garrigue de Chêne kermès à partir des températures et des vitesses de propagation , 1979 .

[23]  L. Trabaud,et al.  Comparative study of the aerial structure of five shrubs of Mediterranean shrublands , 1991 .

[24]  J. T. Gray,et al.  Community Structure and Productivity in Ceanothus Chaparral and Coastal Sage Scrub of Southern California , 1982 .

[25]  M. de Luis,et al.  Factors influencing fire behaviour in shrublands of different stand ages and the implications for using prescribed burning to reduce wildfire risk. , 2002, Journal of environmental management.

[26]  Ross A. Bradstock,et al.  Soil temperatures during bushfires in semi‐arid, mallee shrublands , 1992 .

[27]  S. Botelho,et al.  PRESCRIBED FIRE BEHAVIOR AND FUEL CONSUMPTION IN NORTHERN PORTUGAL AND GALIZA MARITIME PINE STANDS , 1994 .

[28]  Ross A. Bradstock,et al.  Soil Temperatures During Experimental Bushfires in Relation to Fire Intensity: Consequences for Legume Germination and Fire Management in South-Eastern Australia , 1995 .

[29]  Martin E. Alexander,et al.  Calculating and interpreting forest fire intensities , 1982 .

[30]  F. D. Viqueira,et al.  Influencia del fuego en la escorrentía de una ladera = Influence of wildland fire on surface runoff from a hillslope , 1993 .

[31]  Paulo M. Fernandes,et al.  Fire spread prediction in shrub fuels in Portugal , 2001 .

[32]  D. Gillon,et al.  Heat-Transfer in the Soil During Very Low-Intensity Experimental Fires - the Role of Duff and Soil-Moisture Content , 1994 .

[33]  Craig C. Chandler,et al.  Fire in Forestry , 1991 .

[34]  R. Burgan,et al.  BEHAVE : Fire Behavior Prediction and Fuel Modeling System -- FUEL Subsystem , 1984 .

[35]  C. Chandler.  Forest fire behavior and effects , 1983 .

[36]  F. Niell,et al.  Mobilization of nutrients by fire in a semiarid gorse‐scrubland ecosystem of Southern Spain , 1995 .

[37]  P. Cheney,et al.  Fire in forestry. Volume 1. Forest fire behavior and effects. Volume 2. Forest fire management and organization. , 1983 .

[38]  Antonio Alonso de la Torre García,et al.  Suelos y vegetación en el Alto Vinalopó , 1996 .

[39]  L. M. E. Martín,et al.  Inflamabilidad y energía de las especies de sotobosque , 1989 .

[40]  M. Molina,et al.  Soil water dynamics in burned areas after a late summer rain. The role of fire intensity, microsite, sampling depth, and time of measurement. , 1970 .

[41]  M. Molina,et al.  Temperature-time curves at the soil surface in maquis summer fires , 2001 .

[42]  C. Conrad,et al.  THE EFFECT OF FIRE ON NUTRIENTS IN A CHAPARRAL ECOSYSTEM , 1978 .

[43]  N. Cheney,et al.  The Influence of Fuel, Weather and Fire Shape Variables on Fire-Spread in Grasslands , 1993 .

[44]  W. Oechel,et al.  Fire Intensity Effects on Germination of Shrubs and Herbs in Southern California Chaparral , 1991 .

[45]  J. Mateu,et al.  Allometric regression equations to determine aerial biomasses of Mediterranean shrubs , 1997, Plant Ecology.

[46]  B. Berna,et al.  Aspectos ecológicos y técnicas de control del combustible (roza y quema controlada) en matorrales con alto riesgo de incendio, dominados por Ulex parviflorus (Pourr.) , 2001 .

[47]  R. Specht.  A comparison of the sclerophyllous vegetation characteristic of Mediterranean type climates in France, California, and Southern Australia. II. Dry matter, energy, and nutrient accumulation , 1969 .

[48]  A. Gill,et al.  Coupled soil moisture, heat and water vapour transfers under simulated fire conditions , 1976 .

[49]  R. Whelan,et al.  Post-fire Germination of Hakea sericea and Petrophile sessilis after Spring Burning , 1998 .